Age-related changes in responsiveness to non-invasive brain stimulation neuroplasticity paradigms: A systematic review with meta-analysis

OBJECTIVES

We aimed to summarise and critically appraise the available evidence for the effect of age on responsiveness to non-invasive brain stimulation (NBS) paradigms delivered to the primary motor cortex.

METHODS

Four databases (Medline, Embase, PsycINFO and Scopus) were searched from inception to February 7, 2023. Studies investigating age group comparisons and associations between age and neuroplasticity induction from NBS paradigms were included. Only studies delivering neuroplasticity paradigms to the primary motor cortex and responses measured via motor-evoked potentials (MEPs) in healthy adults were considered.

RESULTS

39 studies, encompassing 40 experiments and eight NBS paradigms were included: paired associative stimulation (PAS; n = 12), repetitive transcranial magnetic stimulation (rTMS; n = 2), intermittent theta burst stimulation (iTBS; n = 8), continuous theta burst stimulation (cTBS; n = 7), transcranial direct and alternating current stimulation ((tDCS; n = 7; tACS; n = 2)), quadripulse stimulation (QPS; n = 1) and i-wave periodic transcranial magnetic stimulation (iTMS; n = 1). Pooled findings from PAS paradigms suggested older adults have reduced post-paradigm responses, although there was considerable heterogeneity. Mixed results were observed across all other NBS paradigms and post-paradigm timepoints.

CONCLUSIONS/SIGNIFICANCE

Whilst age-dependent reduction in corticospinal excitability is possible, there is extensive inter- and intra-individual variability both within and between studies, making it difficult to draw meaningful conclusions from pooled analyses.

Painful distortions: people with painful knee osteoarthritis have biased visuospatial perception of the environment

ABSTRACT

Visuospatial perception is thought to be adaptive-ie, hills are perceived as steeper when capacity is low, or threat is high-guiding appropriate interaction with the environment. Pain (bodily threat) may similarly modulate visuospatial perception, with the extent of modulation influenced by threat magnitude (pain intensity, fear) and associated with behaviour (physical activity). We compared visuospatial perception of the environment between 50 people with painful knee osteoarthritis and 50 age-/sex-matched pain-free control participants using 3 virtual reality tasks (uphill steepness estimation, downhill steepness estimation, and a distance-on-hill measure), exploring associations between visuospatial perception, clinical characteristics (pain intensity, state and trait fear), and behaviour (wrist-worn accelerometry) within a larger knee osteoarthritis group (n = 85). People with knee osteoarthritis overestimated uphill (F1,485 = 19.4, P < 0.001) and downhill (F1,480 = 32.3, P < 0.001) steepness more so than pain-free controls, but the groups did not differ for distance-on-hill measures (U = 1273, P = 0.61). There was also a significant group x steepness interaction for the downhill steepness task (F4,480 = 3.11, P = 0.02). Heightened overestimation in people with knee osteoarthritis relative to pain-free controls increased as downhill slopes became steeper. Results were unchanged in a replication analysis using all knee osteoarthritis participants (n = 85), except the downhill steepness interaction was no longer significant. In people with knee osteoarthritis, higher state fear was associated with greater over-estimation of downhill slope steepness (rho = 0.69, P < 0.001), and greater visuospatial overestimation (distance-on-hill) was associated with lower physical activity levels (rho = -0.22, P = 0.045). These findings suggest that chronic pain may shift perception of the environment in line with protection, with overestimation heightened when threat is greater (steeper hills, more fearful), although impact on real-world behaviour is uncertain.

People with painful knee osteoarthritis hold negative implicit attitudes towards activity

ABSTRACT

Negative attitudes/beliefs surrounding osteoarthritis, pain, and activity contribute to reduced physical activity in people with knee osteoarthritis (KOA). These attitudes/beliefs are assessed using self-report questionnaires, relying on information one is consciously aware of and willing to disclose. Automatic (ie, implicit) assessment of attitudes does not rely on conscious reflection and may identify features unique from self-report. We developed an implicit association test that explored associations between images of a person moving/twisting their knee (activity) or sitting/standing (rest), and perceived threat (safe vs dangerous). We hypothesised that people with KOA would have greater implicit threat-activity associations (vs pain-free and non-knee pain controls), with implicit attitudes only weakly correlating with self-reported measures (pain knowledge, osteoarthritis/pain/activity beliefs, fear of movement). Participants (n = 558) completed an online survey: 223 had painful KOA (n = 157 female, 64.5 ± 8.9 years); 207 were pain free (n = 157 female, 49.3 ± 15.3 years); and 99 had non-KOA lower limb pain (n = 74 female, 47.5 ± 15.04 years). An implicit association between "danger" and "activity" was present in those with and without limb pain (KOA: 0.36, 95% CI 0.28-0.44; pain free: 0.13, 95% CI 0.04-0.22; non-KOA lower limb pain 0.11, 95% CI -0.03 to 0.24) but was significantly greater in the KOA group than in the pain free (P < 0.001) and non-KOA lower limb pain (P = 0.004) groups. Correlations between implicit and self-reported measures were nonsignificant or weak (rho = -0.29 to 0.19, P < 0.001 to P = 0.767). People with painful KOA hold heightened implicit threat-activity associations, capturing information unique to that from self-report questionnaires. Evaluating links between implicit threat-activity associations and real-world behaviour, including physical activity levels, is warranted.

Waiting in Pain II: An Updated Analysis of the Multidisciplinary Staffing Levels and Clinical Activity in Australian Specialist Persistent Pain Services

This study provides an update on multidisciplinary staffing and clinical activity in Australian specialist persistent pain services. Of the 109 services identified, 57 responded, met inclusion criteria and completed a study-specific questionnaire detailing service characteristics, staff resources, and clinical activities. Where possible, data were compared between the 'Waiting in Pain' (WIP) investigations (WIP-I: Dec'08-Jan'10, WIP-II: Jul'16-Feb'18). WIP-II found more pain services (Level 1 centres, rural services) and more full-time equivalent (FTE) staffing (overall, psychiatry, psychology, occupational therapy) than WIP-I. Although Level 1 centres employed more FTE staff (overall, medical) than Level 2 clinics, staffing was comparable when considered relative to clinical activity and this was stable over time for most disciplines. Clinical activity in metropolitan and rural services also remained stable, as did rural service staffing (type, FTE), suggesting that newer clinics replicated existing models. WIP-II highlighted greater diversity in group structures than WIP-I and an associated mean .02FTE allied health staff/patient seen (WIP-I = .03 FTE). Staffing (amounts, types) did not change significantly over time when considered relative to clinical activity, supporting the conclusion that these are workable clinical structures. However, changes in group format (duration, staffing) suggest a shift towards lower-intensity programmes that require less allied health staffing to deliver. PERSPECTIVE: This article presents updated data regarding multidisciplinary staffing profiles, clinical activity, and group programme structures within Australian specialist persistent pain services and examines changes since the original investigation. As the only published staffing profile for multidisciplinary pain services, this project provides critical information to inform service (re)design and care delivery.

Mechanisms of education and graded sensorimotor retraining in people with chronic low back pain: a mediation analysis

ABSTRACT

An improved understanding of the biopsychosocial influences that contribute to and maintain pain has promoted the development of new efficacious treatments for chronic low back pain (CLBP). This study aimed to investigate the mechanisms of a new treatment-education and graded sensorimotor retraining-on pain and disability. We conducted a preplanned causal mediation analysis of a randomized clinical trial which allocated 276 participants with CLBP to 12 weekly clinical sessions of education and graded sensorimotor retraining (n = 138) or a sham and attention control (n = 138). Outcomes were pain intensity and disability, both assessed at 18 weeks. Hypothesized mediators included tactile acuity, motor coordination, back self-perception, beliefs about the consequences of back pain, kinesiophobia, pain self-efficacy, and pain catastrophizing, all assessed at the end of treatment (12 weeks). Four of 7 mechanisms (57%) mediated the intervention effect on pain; the largest mediated effects were for beliefs about back pain consequences (-0.96 [-1.47 to -0.64]), pain catastrophizing (-0.49 [-0.61 to -0.24]), and pain self-efficacy (-0.37 [-0.66 to -0.22]). Five of 7 mechanisms (71%) mediated the intervention effect on disability; the largest mediated effects were for beliefs about back pain consequences (-1.66 [-2.62 to -0.87]), pain catastrophizing (-1.06 [-1.79 to -0.53]), and pain self-efficacy (-0.84 [-1.89 to -0.45]). When all 7 mechanisms were considered simultaneously, the joint mediation effect explained most of the intervention effect for both pain and disability. Optimizing interventions to target beliefs about the consequences of back pain, pain catastrophizing, and pain self-efficacy is likely to lead to improved outcomes for people with CLBP.

What I see and what I feel: the influence of deceptive visual cues and interoceptive accuracy on affective valence and sense of effort during virtual reality cycling

Background

How we feel during exercise is influenced by exteroceptive (e.g., vision) and interoceptive (i.e., internal body signals) sensory information, and by our prior experiences and expectations. Deceptive visual cues about one's performance during exercise can increase work rate, without negatively impacting affective valence (good/bad responses) or perceived exertion. However, what is less understood is whether the perception of the exercise experience itself can be shifted, if work rate is held constant. Here we aimed to investigate whether deceptive vision-via illusory hills in a virtual reality (VR) cycling experience-alters affective valence and perceived exertion when physical effort is controlled. We also evaluated whether the accuracy with which one detects interoceptive cues influences the extent to which deceptive visual information can shift exercise experiences.

Methods

A total of 20 participants (10 female; 30.2 ± 11.2 yrs) completed three VR cycling conditions each of 10-min duration, in a randomised, counterbalanced order. Pedal resistance/cadence were individualised (to exercise intensity around ventilatory threshold) and held constant across conditions; only visual cues varied. Two conditions provided deceptive visual cues about the terrain (illusory uphill, illusory downhill; resistance did not change); one condition provided accurate visual cues (flat terrain). Ratings of affective valence (Feeling Scale) and of perceived exertion (Borg's RPE) were obtained at standardised timepoints in each VR condition. Interoceptive accuracy was measured via a heartbeat detection test.

Results

Linear mixed effects models revealed that deceptive visual cues altered affective valence (f2 = 0.0198). Relative to flat terrain, illusory downhill reduced affective valence (Est = -0.21, p = 0.003), but illusory uphill did not significantly improve affective valence (Est = 0.107, p = 0.14). Deceptive visual cues altered perceived exertion, and this was moderated by the level of interoceptive accuracy (Condition-Interoception interaction, p = 0.00000024, f2 = 0.0307). Higher levels of interoceptive accuracy resulted in higher perceived exertion in the illusory downhill condition (vs flat), while lower interoceptive accuracy resulted in lower perceived exertion in both illusory hill conditions (vs flat) and shifts of greater magnitude.

Conclusions

Deceptive visual cues influence perceptual responses during exercise when physical effort does not vary, and for perceived exertion, the weighting given to visual exteroceptive cues is determined by accuracy with which interoceptive cues are detected. Contrary to our hypotheses, deceptive visual cues did not improve affective valence. Our findings suggest that those with lower levels of interoceptive accuracy experience most benefit from deceptive visual cues, providing preliminary insight into individualised exercise prescription to promote positive (and avoid negative) exercise experiences.

Item development and pre-testing of an Osteoarthritis Conceptualisation Questionnaire to assess knowledge and beliefs in people with knee pain

Many people with osteoarthritis hold beliefs that physical activity is unhelpful or dangerous for their joints, despite high-level evidence suggesting otherwise. Recent advances in scientific understanding of osteoarthritis have led to new treatments that target an individual's understanding both of their condition and the importance of best-practice management strategies, such as physical activity. Conceptual change has been proposed as an important mechanism by which cognitive interventions, such as pain science education, may reduce pain and improve function. There are currently no specific assessments of osteoarthritis conceptualisation to determine the effectiveness of cognitive interventions in effecting conceptual change in people with knee osteoarthritis. Therefore, we aimed to develop an item bank, as the first phase of developing a questionnaire to assess people's conceptualisations about their knee osteoarthritis and the role of physical activity in managing their osteoarthritis. Using a guideline-informed mixed method design, a panel of experts identified domains relevant to conceptualisation about knee osteoarthritis and physical activity (knowledge, beliefs, understanding) based upon available evidence. The panel created 33 provisional items. Qualitative and quantitative pretesting were used to explore how people with knee osteoarthritis understood the provisional items. Eighteen people with knee osteoarthritis completed cognitive interviews about their comprehension of the wording/grammar of each provisional item. The provisional item bank was field tested with 100 people with knee osteoarthritis. Readability was adequate with a Flesch reading ease score of 57.7. Although 14.7% used the 'Strongly agree' response option, only 3.4% of responses used the 'Strongly disagree' option, suggesting possible response bias. Predictive quality testing identified relevant modifications to the questionnaire instructions. The panel of experts appraised the qualitative data to assess whether and how items should be modified to address the problems identified, resulting in a final item bank of 45 items that can be evaluated for psychometric properties in future research.

Get Your Head in the Game: A Replicated Single-Case Experimental Design Evaluating the Effect of a Novel Virtual Reality Intervention in People With Chronic Low Back Pain

Chronic low back pain (CLBP) is a leading cause of disability worldwide. Contemporary treatment of CLBP is suboptimal, with small-moderate effect sizes and high relapse rates. Virtual reality (VR) is an increasingly accessible technology that can improve adherence to exercise programs through gamification. Using VR to facilitate exercise adherence and enjoyment may improve the clinical outcomes. This study aimed to evaluate the effects of a gamified VR graded activity intervention in people with CLBP, using commercially available and bespoke VR programs. A sequentially replicated, multiple-baseline, randomized AB single-case experimental design was undertaken in 10 people with CLBP. Outcomes were assessed daily and included pain intensity (primary) and pain catastrophizing, pain-related fear, and anxiety/worry (secondary). The effect of the intervention on the primary outcome was evaluated using a multilevel-model, nonparametric randomization test. The VR graded activity intervention resulted in a significant reduction in pain intensity (effect estimate = -1.0, standard error = .27, P < .0011) with 4 participants achieving ≥30% pain reduction (minimum important change). There was a significant effect of the intervention on pain catastrophizing but not pain-related fear or anxiety/worry measures. These findings provide preliminary support for a VR graded activity program to reduce pain in people with CLBP. PERSPECTIVE: This novel, VR graded activity intervention reduced pain intensity and catastrophizing in people with CLBP. The intervention also had high adherence and enjoyment. Given that this intervention involved 2 freely available VR programs, it can be easily translated into clinical practice.

Osteoarthritis consumers as co-researchers: Identifying consumer insights to improve osteoarthritis management by co-designing translational research solutions

INTRODUCTION

Co-design is a consumer-driven approach that facilitates consumer participation in creating meaningful solutions to complex problems. Poor uptake of core management strategies for osteoarthritis suggests there is a missing link in translation between research and practice. We partnered with osteoarthritis consumers as 'co-researchers' to identify translational research solutions to improve uptake of core management strategies that are grounded in lived experiences.

OBJECTIVE

To transparently describe a theory-driven, generative co-design approach using an integrated conceptual framework to collaborate with consumers at the equal partnership level.

DESIGN

We used co-design workshops with a non-hierarchical participatory framework. Three workshops with six co-researchers [2 female, mean age 68.7(9.8) years, 3-30 years symptom duration] were conducted using activities to encourage creative thinking, promote deep reflection on personal/societal beliefs and minimise sensitivities around sharing personal beliefs (e.g., establishing a safe space, prompting questions, perspective-taking, counter-stereotypical exemplars).

RESULTS

All six co-researchers actively participated in the workshops. Achievement of an equal collaborative partnership was evidenced by co-researchers challenging a project proposed by the research team and making alternative recommendations that have been implemented in prospective decision-making - representing a complete change in research focus driven by consumer input. A key suggested solution was to develop a scalable knowledge translation intervention that targets misconceptions about osteoarthritis and its management at the societal-level.

CONCLUSIONS

Through an innovative co-design approach in partnership with co-researchers, we identified meaningful areas on which to focus translational research for osteoarthritis. Discordance between existing research priorities and novel solutions proposed by co-researchers highlights the value of co-design.

The Foundations for Chronic Low Back Pain Management may Start in Early Life. Exploring the Role of Caregiver Parental Leave on Future Low Back Pain in the Offspring

Chronic low back pain is difficult to treat and despite increased spending on health services, clinical outcomes for people with low back pain have not improved. Innovative, large scale initiatives seem necessary to stem the cost of low back pain. Psychological health contributes to the development and persistence of chronic low back pain and psychological interventions are important in the management of low back pain. Given the contribution of psychological health to low back pain development and management, it raises the question; can we support psychological health in later life by bolstering emotional development in early life, and reduce the burden of this common condition? Positive early life experiences, including those induced by extended paid parental leave, could bolster emotional development and support the psychological health necessary to manage low back pain in later life. We present the current state of evidence demonstrating the potential value of increasing support for parent-child relationships in early life to reduce the burden of low back pain in future generations. The current evidence is limited to cross-sectional associations, but strong preclinical data clearly shows the potential negative impacts of maternal separation on rodent pup health that compels consideration in human populations. PERSPECTIVE: The benefits stemming from enhanced child development include stable emotional foundations, possibly improving psychological health and low back pain management in the future. This perspective raises questions for future studies - within the context of low back pain, what ingredients bolster stable psychological health? And are these ingredients influenced by parental leave?

Key Learning Statements for persistent pain education: an iterative analysis of consumer, clinician and researcher perspectives and development of public messaging

Over the last decade, the content, delivery and media of pain education have been adjusted in line with scientific discovery in pain and educational sciences, and in line with consumer perspectives. This paper describes a decade-long process of exploring consumer perspectives on pain science education concepts to inform clinician-derived educational updates (undertaken by the authors). Data were collected as part of a quality audit via a series of online surveys in which consent (non-specific) was obtained from consumers for their data to be used in published research. Consumers who presented for care for a persistent pain condition and were treated with a pain science education informed approach were invited to provide anonymous feedback about their current health status and pain journey experience 6, 12 or 18 months after initial assessment. Two-hundred eighteen consumers reported improvement in health status at follow-up. Results of the surveys from three cohorts of consumers that reported improvement were used to generate iterative versions of 'Key Learning Statements'. Early iteration of these Key Learning Statements was used to inform the development of Target Concepts and associated community-targeted pain education resources for use in public health and health professional workforce capacity building initiatives. Perspective This paper reflects an explicit interest in the insights of people who have been challenged by persistent pain and then recovered, to improve pain care. Identifying pain science concepts that consumers valued learning provided valuable information to inform resources for clinical interactions and community-targeted pain education campaigns.

Effect of Graded Sensorimotor Retraining on Pain Intensity in Patients With Chronic Low Back Pain: A Randomized Clinical Trial

IMPORTANCE

The effects of altered neural processing, defined as altering neural networks responsible for perceptions of pain and function, on chronic pain remains unclear.

OBJECTIVE

To estimate the effect of a graded sensorimotor retraining intervention (RESOLVE) on pain intensity in people with chronic low back pain.

DESIGN, SETTING, AND PARTICIPANTS

This parallel, 2-group, randomized clinical trial recruited participants with chronic (>3 months) nonspecific low back pain from primary care and community settings. A total of 276 adults were randomized (in a 1:1 ratio) to the intervention or sham procedure and attention control groups delivered by clinicians at a medical research institute in Sydney, Australia. The first participant was randomized on December 10, 2015, and the last was randomized on July 25, 2019. Follow-up was completed on February 3, 2020.

INTERVENTIONS

Participants randomized to the intervention group (n = 138) were asked to participate in 12 weekly clinical sessions and home training designed to educate them about and assist them with movement and physical activity while experiencing lower back pain. Participants randomized to the control group (n = 138) were asked to participate in 12 weekly clinical sessions and home training that required similar time as the intervention but did not focus on education, movement, and physical activity. The control group included sham laser and shortwave diathermy applied to the back and sham noninvasive brain stimulation.

MAIN OUTCOMES AND MEASURES

The primary outcome was pain intensity at 18 weeks, measured on an 11-point numerical rating scale (range, 0 [no pain] to 10 [worst pain imaginable]) for which the between-group minimum clinically important difference is 1.0 point.

RESULTS

Among 276 randomized patients (mean [SD] age, 46 [14.3] years; 138 [50%] women), 261 (95%) completed follow-up at 18 weeks. The mean pain intensity was 5.6 at baseline and 3.1 at 18 weeks in the intervention group and 5.8 at baseline and 4.0 at 18 weeks in the control group, with an estimated between-group mean difference at 18 weeks of -1.0 point ([95% CI, -1.5 to -0.4]; P = .001), favoring the intervention group.

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial conducted at a single center among patients with chronic low back pain, graded sensorimotor retraining, compared with a sham procedure and attention control, significantly improved pain intensity at 18 weeks. The improvements in pain intensity were small, and further research is needed to understand the generalizability of the findings.

TRIAL REGISTRATION

ANZCTR Identifier: ACTRN12615000610538.

Suggestions in Hypnosis to Aid Pain Education (SHAPE) in People with Chronic Low-Back Pain: A Pilot Feasibility Randomized, Controlled Trial

Chronic low back pain (CLBP) is a debilitating and burdensome condition, and new treatment strategies are needed. This study aimed to evaluate (1) the feasibility of undertaking a controlled clinical trial investigating a novel intervention for people with CLBP: hypnotically reinforced pain science education, and (2) the acceptability of the intervention as rated by participants. A priori feasibility and intervention acceptability criteria were set. Twenty participants with CLBP were recruited and randomized to receive: (1) hypnotically delivered pain science education that utilizes hypnotic suggestions to enhance uptake of pain science concepts; or (2) pain science education with progressive muscle relaxation as an attention control. Twenty participants were recruited, however, not solely from the hospital waitlist as intended; community sampling was required (13 hospital, 7 community). Most criteria were met in the community sample but not the hospital sample. Protocol modifications are needed before progressing to a full scale randomized controlled trial for hypnotically reinforced pain science education. Improvements in relevant secondary outcomes paired with moderate-high treatment acceptability ratings are promising.

Reframe the pain: Divided attention and positive memory reframing to reduce needle pain and distress in children-A feasibility randomized controlled trial

BACKGROUND

Negative experiences of needle procedures in childhood can lead to medical avoidance and vaccine hesitancy into adulthood. We evaluated the feasibility of two new interventions provided by clinical nurses to reduce the negative impact of vaccinations: divided attention (DA) and positive memory reframing (PMR).

METHODS

Children (8-12 years) were randomized into four groups: usual care (UC), DA, PMR or combined (DA + PMR). To evaluate feasibility, we undertook in-depth analysis of video-recorded interventions, nurse experiences (phone interviews) and child/parent memory recall of interventions (phone interviews at 2 weeks post-vaccination). Key clinical outcomes included child and parent ratings of needle-related pain intensity and fear assessed at baseline, immediately post-vaccination and 2 weeks post-vaccination (recalled).

RESULTS

A total of 54 child-parent dyads were screened, with 41 included (10/group, except PMR [n = 11]). The interventions were not always completed as intended: 10%-22% of participants received complete interventions and two had adverse events related to protocol breach. Preliminary within-group analyses showed no effects on child/parent pain ratings. However, children in DA + PMR had reduced recalled fear (p = 0.008), and PMR (p = 0.025) and DA + PMR (p = 0.003) had reduced fear of future needles. Parent ratings of child fear were also reduced immediately post-vaccination for UC (p = 0.035) and PMR (p = 0.035).

CONCLUSIONS

The interventions were feasible, although enhanced nurse training is required to improve fidelity. Preliminary clinical results appear promising, particularly for reducing needle-related fear.

PROTOCOL REGISTRATION

Protocol number ACTRN12618000687291 at ANZCTR.org.au SIGNIFICANCE: Two new nurse-led interventions to reduce negative impacts of vaccinations in children, divided attention and positive memory reframing, were feasible and may reduce needle-related fear. Nurses were able to deliver the interventions in various environments including non-clinical settings (schools). These interventions have potential to facilitate broader dissemination of vaccinations for children in a manner that minimizes distress.

Does who I am and what I feel determine what I see (or say)? A meta-analytic systematic review exploring the influence of real and perceived bodily state on spatial perception of the external environment

Background

Bodily state is theorised to play a role in perceptual scaling of the environment, whereby low bodily capacity shifts visuospatial perception, with distances appearing farther and hills steeper, and the opposite seen for high bodily capacity. This may play a protective role, where perceptual scaling discourages engaging with the environment when capacity is low.

Methodology

Our protocol was pre-registered via Open Science Framework (https://osf.io/6zya5/) with all amendments to the protocol tracked. We performed a systematic review and meta-analysis examining the role of bodily state/capacity on spatial perception measures of the environment. Databases (Medline, PsychINFO, Scopus, Embase, and Emcare) and grey literature were searched systematically, inclusive to 26/8/21. All studies were assessed using a customised Risk of Bias form. Standard mean differences and 95% CIs were calculated via meta-analysis using a random-effects model.

Results

A total of 8,034 studies were identified from the systematic search. Of these, 68 experiments (3,195 participants) met eligibility and were included in the review. These were grouped into the following categories: fatigue; pain; age; embodiment; body size/body paty size; glucose levels; fitness; and interoception, and interoceptive accuracy. We found low level evidence (limited studies, high risk of bias) for the effect of bodily state on spatial perception. There was consistent evidence that both glucose manipulations and age influence spatial perception of distances and hills in a hypothesised direction (lower capacity associated with increased distance and hill steepness). Mixed evidence exists for the influence of external loads, embodiment, body/body-part size manipulations, pain, and interoceptive accuracy. Evidence for fitness and/or fatigue influencing spatial perception was conflicting; notably, methodological flaws with fitness and fatigue paradigms and heterogenous spatial perception measures may underlie null/conflicting results.

Conclusion

We found limited evidence for bodily state influencing spatial perception of the environment. That all studies had high risk of bias makes conclusions about reported effects reflecting actual perceptual shifts (vs merely reflecting experimental demands or error due to inadequate study design) pre-emptive. Rigorous evaluation is needed to determine whether reported effects reflect more than bias (e.g., experimental demands, inadequate blinding). Future work using reliable measures of spatial perception, comprehensive evaluation of relevant confounders, and methodologically robust (and experimentally confirmed) bodily state experimental paradigms is warranted.

Safety and Adverse Events following Non-invasive Electrical Brain Stimulation in Stroke: A Systematic Review

BACKGROUND

Noninvasive electrical stimulation (ES) could have therapeutic potential in stroke recovery. However, there is no comprehensive evaluation of adverse events. This study systematically searched the literature to document frequency and prevalence of adverse events. A secondary aim was to explore associations between adverse events and ES parameters or participant characteristics.Methods: Databases were searched for studies evaluating ES in adults with stroke. All included studies were required to report on adverse events. Extracted data were: (1) study design; (2) adverse events; (3) participant characteristics; (4) ES parameters.

RESULTS

Seventy-five studies were included. Adverse events were minor in nature. The most frequently reported adverse events were tingling (37.3% of papers), burning (18.7%), headaches (14.7%) and fatigue (14.7%). Cathodal stimulation was associated with greater frequency of itching (p = .02), intensities of 1-2 mA with increased tingling (p = .04) and discomfort (p = .03), and current density <0.4mA/cm2 with greater discomfort (p = .03). Tingling was the most prevalent adverse event (18.1% of participants), with prevalence data not differing between active and control conditions (all p ≥ 0.37). Individual participants were more likely to report adverse events with increasing current density (r = 0.99, p = .001). Two severe adverse events were noted (a seizure and percutaneous endoscopic gastrostomy placement).

CONCLUSION

ES appears safe in people with stroke as reported adverse events were predominantly minor in nature. An adverse events questionnaire is proposed to enable a more comprehensive and nuanced analysis of the frequency and prevalence of adverse events.

Delay and Effort-Based Discounting, and the Role of Bodily Awareness, In People Experiencing Long-Term Pain: A Cross-Sectional Study

Pain interventions typically include effortful exercise and long-term treatment - ie, short-term costs (effort) with delayed benefit (improved pain and/or function). Thus, understanding if long-term pain influences decision-making in context of delays and effort is essential given clear relevance to treatment uptake and/or adherence. We evaluated delay and effort attitudes in those experiencing chronic pain (n = 391) and in pain-free controls (n = 263). Additionally, we investigated the role of bodily sensation awareness and/or interpretation as potential contributing factors to altered decision-making. Volunteers completed three discounting questionnaires, assessing the influence of temporal delays (gains, losses) and effort on devaluation of monetary outcomes. Individuals with chronic pain had more short-sighted decisions for monetary gains, but not losses, and decreased willingness to undertake effort for monetary gains than the No Pain group. The Pain group had higher bodily sensation awareness and while this related to higher impulsivity, delay and effort discounting, neither awareness nor interpretation of bodily sensations interacted with pain levels or explained group differences in discounting behavior. These findings suggest that impaired delay and effort-based discounting is present in people with chronic pain, and that this may be driven by pain-induced changes, but not pain-induced enhancements in bodily sensation awareness and/or interpretation. Exploring the utility of interventions targeting discounting behavior is warranted. Data availability: Study materials are available here: https://osf.io/zexm7/?view_only=c9848597361c41808c612874da6f33b7. PERSPECTIVE: People with chronic pain make more short-sighted decisions (prefer less reward sooner) and decreased willingness to undertake effort (prefer less reward with little effort) for monetary gains than people without pain. Interventions targeting discounting behavior may help improve both uptake and adherence for evidence-based, effortful treatments, such as exercise.

Determining the credibility, accuracy and comprehensiveness of websites educating consumers on complex regional pain syndrome accessible in Australia: a systematic review

Complex regional pain syndrome (CRPS) is a distressing and disabling pain condition. Many people with CRPS and the health professionals who treat them seek information about the condition via the Internet. The credibility, accuracy and comprehensiveness of online CRPS information remains unknown. The aim of this study was to determine the credibility, accuracy and comprehensiveness of information presented on freely accessible websites that aim to educate people about CRPS. Keyword searches were conducted on the Australian Google site, with 'trustworthy' websites included and critically appraised. Primary outcomes were recognised metrics of credibility (JAMA benchmark credibility criteria) and website accuracy (according to European CRPS guidelines). Comprehensiveness was assessed using the proportion of European CRPS guidelines covered by the websites. In all, 30 websites with 819 recommendations were critically appraised. Five (17%) websites met all credibility criteria; of the recommendations, 349 (43%) were accurate, 252 (31%) were inaccurate and 218 (26%) were unclear. For comprehensiveness, an average of 17% of general guidelines, 15% of therapeutic guidelines and 6% of medication/supplement guidelines were covered. Online information about CRPS available to Australians has low credibility, accuracy and comprehensiveness. Many website recommendations are inaccurate or unclear, and many websites endorse inappropriate treatments. There is an urgent need for accurate and comprehensive sources of CRPS information online.

The effect of visually manipulating back size and morphology on back perception, body ownership, and attitudes towards self-capacity during a lifting task

Body re-sizing illusions can profoundly alter perception of our own body. We investigated whether creating the illusion of a muscled and fit-looking back (Strong) influenced perceived back size, body ownership, and attitudes towards self-capacity during a lifting task. Twenty-four healthy male volunteers performed a standardised lifting task while viewing real-time (delay < 20 ms) video of their own back through a head-mounted display under four different conditions (Normal size, Strong, Reshaped, Large; order randomised). The MIRAGE-mediated reality system was used to modify the shape, size, and morphology of the back. Participants were poor at recognizing the correct appearance of their back, for both implicit (perceived width of shoulders and hips) and explicit (questionnaire) measures of back size. Visual distortions of body shape (Reshaped condition) altered implicit back size measures. However, viewing a muscled back (Strong condition) did not result in a sense of agency or ownership and did not update implicit perception of the back. No conditions improved perceptions/attitudes of self-capacity (perceived back strength, perceived lifting confidence, and perceived back fitness). The results lend support for the importance of the embodiment of bodily changes to induce changes in perception. Further work is warranted to determine whether increased exposure to illusory changes would alter perceptions and attitudes towards self-capacity or whether different mechanisms are involved.

What do patients value learning about pain? A mixed-methods survey on the relevance of target concepts after pain science education

ABSTRACT

Pain education is a popular treatment approach for persistent pain that involves learning a variety of concepts about pain (ie, target concepts), which is thought to be an important part of recovery. Yet, little is known about what patients value learning about pain. A mixed-methods survey was conducted to identify pain concepts that were valued by people with persistent pain who improved after a pain science education intervention. An online survey was distributed to 123 people who were treated for persistent pain with a pain science education approach; responses of participants who self-identified as "improved" were analysed. Open-ended survey questions were analysed using reflexive thematic analysis and close-ended questions were analysed for frequency of responses. Each question-type was analysed separately, before integration for complementarity. We analysed the data of 97 participants. We constructed 3 themes from the open-ended questions. Pain does not mean my body is damaged (theme 1) captured the importance of abandoning preexisting ideas that pain indicated damage. Thoughts, emotions and experiences affect pain (theme 2) captured the value of recognising multifactorial influences on pain. I can retrain my overprotective pain system (theme 3) captured the importance of conceptualising pain as a heightened protective response that could be lessened. Responses from close-ended questions confirmed that the target concepts represented by these themes are among those most valued, although divergence with the qualitative data suggests differences between patient and clinician language. These data offer patient-centred conceptualizations and language that could assist in further refining pain education interventions.

Implicit motor imagery of the foot and hand in people with Achilles tendinopathy: a left right judgement study

OBJECTIVE

To determine if impairment in motor imagery processes is present in Achilles tendinopathy (AT), as demonstrated by a reduced ability to quickly and accurately identify the laterality (left-right judgement) of a pictured limb. Additionally, this study aimed to use a novel data pooling approach to combine data collected at 3 different sites via meta-analytical techniques that allow exploration of heterogeneity.

DESIGN

Multi site case-control study.

METHODS

Three independent studies with similar protocols were conducted by separate research groups. Each study-site evaluated left/right judgement performance for images of feet and hands using Recognise© software and compared performance between people with AT and healthy controls. Results from each study-site were independently collated, then combined in a meta-analysis.

RESULTS

126 participants (40 unilateral, 22 bilateral AT cases, 61 controls) were included. There were no differences between AT cases and controls for hand image accuracy and reaction time. Contrary to the hypothesis, there were no differences in performance between those with AT and controls for foot image reaction time, however there were conflicting findings for foot accuracy, based on four separate analyses. There were no differences between the affected and unaffected sides in people with unilateral AT.

CONCLUSIONS

Impairments in motor imagery performance for hands were not found in this study and we found inconsistent results for foot accuracy. This contrasts to studies in persistent pain of limbs, face and knee osteoarthritis, and suggests that differences in pathoaetiology or patient demographics may uniquely influence proprioceptive representation.

Where is my arm? Investigating the link between complex regional pain syndrome and poor localisation of the affected limb

Background

Anecdotally, people living with Complex Regional Pain Syndrome (CRPS) often report difficulties in localising their own affected limb when it is out of view. Experimental attempts to investigate this report have used explicit tasks and yielded varied results.

Methods

Here we used a limb localisation task that interrogates implicit mechanisms because we first induce a compelling illusion called the Disappearing Hand Trick (DHT). In the DHT, participants judge their hands to be close together when, in fact, they are far apart. Sixteen volunteers with unilateral upper limb CRPS (mean age 39 ± 12 years, four males), 15 volunteers with non-CRPS persistent hand pain (‘pain controls’; mean age 58 ± 13 years, two males) and 29 pain-free volunteers (‘pain-free controls’; mean age 36 ± 19 years, 10 males) performed a hand-localisation task after each of three conditions: the DHT illusion and two control conditions in which no illusion was performed. The conditions were repeated twice (one for each hand). We hypothesised that (1) participants with CRPS would perform worse at hand self-localisation than both the control samples; (2) participants with non-CRPS persistent hand pain would perform worse than pain-free controls; (3) participants in both persistent pain groups would perform worse with their affected hand than with their unaffected hand.

Results

Our first two hypotheses were not supported. Our third hypothesis was supported —when visually and proprioceptively encoded positions of the hands were incongruent (i.e. after the DHT), relocalisation performance was worse with the affected hand than it was with the unaffected hand. The similar results in hand localisation in the control and pain groups might suggest that, when implicit processes are required, people with CRPS’ ability to localise their limb is preserved.

The EPIPHA-KNEE trial: Explaining Pain to target unhelpful pain beliefs to Increase PHysical Activity in KNEE osteoarthritis - a protocol for a multicentre, randomised controlled trial with clinical- and cost-effectiveness analysis

Background

Despite well-established benefits of physical activity for knee osteoarthritis (OA), nine of ten people with knee OA are inactive. People with knee OA who are inactive often believe that physical activity is dangerous, fearing that it will further damage their joint(s). Such unhelpful beliefs can negatively influence physical activity levels. We aim to evaluate the clinical- and cost-effectiveness of integrating physiotherapist-delivered pain science education (PSE), an evidence-based conceptual change intervention targeting unhelpful pain beliefs by increasing pain knowledge, with an individualised walking, strengthening, and general education program.

Methods

Two-arm, parallel-design, multicentre randomised controlled trial involving 198 people aged ≥50 years with painful knee OA who do not meet physical activity guideline recommendations or walk regularly for exercise. Both groups receive an individualised physiotherapist-led walking, strengthening, and OA/activity education program via 4x weekly in-person treatment sessions, followed by 4 weeks of at-home activities (weekly check-in via telehealth), with follow-up sessions at 3 months (telehealth) and 5 and 9 months (in-person). The EPIPHA-KNEE group also receives contemporary PSE about OA/pain and activity, embedded into all aspects of the intervention. Outcomes are assessed at baseline, 12 weeks, 6 and 12 months. Primary outcomes are physical activity level (step count; wrist-based accelerometry) and self-reported knee symptoms (WOMAC Total score) at 12 months. Secondary outcomes are quality of life, pain intensity, global rating of change, self-efficacy, pain catastrophising, depression, anxiety, stress, fear of movement, knee awareness, OA/activity conceptualisation, and self-regulated learning ability. Additional measures include adherence, adverse events, blinding success, COVID-19 impact on activity, intention to exercise, treatment expectancy/perceived credibility, implicit movement/environmental bias, implicit motor imagery, two-point discrimination, and pain sensitivity to activity. Cost-utility analysis of the EPIPHA-KNEE intervention will be undertaken, in addition to evaluation of cost-effectiveness in the context of primary trial outcomes.

Discussion

We will determine whether the integration of PSE into an individualised OA education, walking, and strengthening program is more effective than receiving the individualised program alone. Findings will inform the development and implementation of future delivery of PSE as part of best practice for people with knee OA.

Trial registration

Australian New Zealand Clinical Trials Registry: ACTRN12620001041943 (13/10/2020).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04561-6.

Investigating the Mechanisms of Graded Sensorimotor Precision Training in Adults With Chronic Nonspecific Low Back Pain: Protocol for a Causal Mediation Analysis of the RESOLVE Trial

Background

Chronic low back pain (CLBP) is a global health problem associated with an increasing burden on individuals, health care systems, and society. Common treatments for people with CLBP produce, on average, small short-term improvements in pain and function compared with minimal care. The RESOLVE trial randomly allocated 276 people with CLBP to a new complex treatment strategy, pain education integrated with graded sensorimotor precision training (RESOLVE), or a sham control. The RESOLVE treatment was developed within a theoretical framework to target possible treatment mechanisms associated with CLBP development and persistence.

Objective

This protocol describes the planned evaluation of these proposed treatment mechanisms. Improved understanding of the mechanisms underpinning the RESOLVE treatment may guide its refinement and implementation.

Methods

We will use causal mediation analysis to evaluate the proposed treatment mechanisms, including pain self-efficacy, back beliefs, pain catastrophizing, kinesiophobia, back perception, tactile acuity, and movement coordination. The primary outcomes are pain intensity and function at 18 weeks following allocation. Data were collected blind to allocation and hypotheses at baseline (mediators, outcomes, confounders), end of treatment (mediators), and at 18 weeks following allocation (outcomes). We will test the robustness of our findings by conducting planned sensitivity analyses.

Results

Ethical approval was granted by the University of New South Wales Human Research Ethics Committee (HC15357). A total of 276 participants have been recruited from primary care practices and the community in Sydney, Australia.

Conclusions

The RESOLVE treatment constitutes a new paradigm for CLBP management with potentially wide-reaching implications. This mechanistic evaluation will provide evidence for the hypothesized treatment mechanisms and help explain why the treatment strategy did or did not have an effect on patient-reported outcomes. These results will help guide the treatment refinement and implementation.

Trial Registration

Australian and New Zealand Clinical Trials Registry ACTRN12615000610538; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=368619&isReview=true

International Registered Report Identifier (IRRID)

DERR1-10.2196/26053

Imprecise Visual Feedback About Hand Location Increases a Classically Conditioned Pain Expectancy Effect

We tested the hypotheses that rendering sensory input about hand location imprecise increases a classically conditioned pain expectancy effect, increases generalization of the effect to novel locations and reduces extinction of the effect. Forty healthy volunteers performed movements with their right hand along predefined paths. Each path passed through 2 locations that were defined as either i) the conditioned stimulus (CS+; paired with a painful unconditioned stimulus), or ii) unpaired (CS-). During acquisition phase, participants watched their hand as they moved it. Participants were randomly allocated to an Imprecise group, for whom visual feedback of the hand was offset 30 to 50 mm from its true location, or a Precise group, for whom vision was not disrupted. In the test phase, participants moved their hands to 5 locations-the CS+, CS-, and 3 locations that lay between the 2 ("generalization stimuli"). Our primary hypothesis was supported-pain expectancy was greater at the CS+ location in the Imprecise group than in the Precise group (6.9 [SD = 1.9] vs 5.4 [SD = 2.5], P= .02). Pain expectancies generalized to novel locations similarly in both groups and there was no difference in extinction between groups. Our primary hypothesis was supported but our subsequent hypotheses were not. PERSPECTIVE: We conditioned pain expectancy at a certain location of one hand, even though most participants were unaware of the contingency. Conditioned pain expectancy was greater when sensory information about location was less precise. This adds support to the possibility that associative learning may play a role in the progression of an acute pain episode to a more generalized pain disorder.

Assessing kinesthetic proprioceptive function of the upper limb: a novel dynamic movement reproduction task using a robotic arm

Background

Proprioception refers to the perception of motion and position of the body or body segments in space. A wide range of proprioceptive tests exists, although tests dynamically evaluating sensorimotor integration during upper limb movement are scarce. We introduce a novel task to evaluate kinesthetic proprioceptive function during complex upper limb movements using a robotic device. We aimed to evaluate the test–retest reliability of this newly developed Dynamic Movement Reproduction (DMR) task. Furthermore, we assessed reliability of the commonly used Joint Reposition (JR) task of the elbow, evaluated the association between both tasks, and explored the influence of visual information (viewing arm movement or not) on performance during both tasks.

Methods

During the DMR task, participants actively reproduced movement patterns while holding a handle attached to the robotic arm, with the device encoding actual position throughout movement. In the JR task, participants actively reproduced forearm positions; with the final arm position evaluated using an angle measurement tool. The difference between target movement pattern/position and reproduced movement pattern/position served as measures of accuracy. In study 1 (N = 23), pain-free participants performed both tasks at two test sessions, 24-h apart, both with and without visual information available (i.e., vision occluded using a blindfold). In study 2 (N = 64), an independent sample of pain-free participants performed the same tasks in a single session to replicate findings regarding the association between both tasks and the influence of visual information.

Results

The DMR task accuracy showed good-to-excellent test–retest reliability, while JR task reliability was poor: measurements did not remain sufficiently stable over testing days. The DMR and JR tasks were only weakly associated. Adding visual information (i.e., watching arm movement) had different performance effects on the tasks: it increased JR accuracy but decreased DMR accuracy, though only when the DMR task started with visual information available (i.e., an order effect).

Discussion

The DMR task’s highly standardized protocol (i.e., largely automated), precise measurement and involvement of the entire upper limb kinetic chain (i.e., shoulder, elbow and wrist joints) make it a promising tool. Moreover, the poor association between the JR and DMR tasks indicates that they likely capture unique aspects of proprioceptive function. While the former mainly captures position sense, the latter appears to capture sensorimotor integration processes underlying kinesthesia, largely independent of position sense. Finally, our results show that the integration of visual and proprioceptive information is not straightforward: additional visual information of arm movement does not necessarily make active movement reproduction more accurate, on the contrary, when movement is complex, vision appears to make it worse.

Intact tactile anisotropy despite altered hand perception in complex regional pain syndrome: rethinking the role of the primary sensory cortex in tactile and perceptual dysfunction

Complex Regional Pain Syndrome (CRPS) is characterised by pain, autonomic, sensory and motor abnormalities. It is associated with changes in the primary somatosensory cortex (S1 representation), reductions in tactile sensitivity (tested by two-point discrimination), and alterations in perceived hand size or shape (hand perception). The frequent co-occurrence of these three phenomena has led to the assumption that S1 changes underlie tactile sensitivity and perceptual disturbances. However, studies underpinning such a presumed relationship use tactile sensitivity paradigms that involve the processing of both non-spatial and spatial cues. Here, we used a task that evaluates anisotropy (i.e., orientation-dependency; a feature of peripheral and S1 representation) to interrogate spatial processing of tactile input in CRPS and its relation to hand perception. People with upper limb CRPS (n = 14) and controls with (n = 15) or without pain (n = 19) judged tactile distances between stimuli-pairs applied across and along the back of either hand to provide measures of tactile anisotropy. Hand perception was evaluated using a visual scaling task and questionnaires. Data were analysed with generalised estimating equations. Contrary to our hypotheses, tactile anisotropy was bilaterally preserved in CRPS, and the magnitude of anisotropic perception bias was comparable between groups. Hand perception was distorted in CRPS but not related to the magnitude of anisotropy or bias. Our results suggest against impairments in spatial processing of tactile input, and by implication S1 representation, as the cause of distorted hand perception in CRPS. Further work is warranted to elucidate the mechanisms of somatosensory dysfunction and distorted hand perception in CRPS.

Using Mediation Analysis to Understand How Treatments for Paediatric Pain Work: A Systematic Review and Recommendations for Future Research

Clinicians have an increasing number of evidence-based interventions to treat pain in youth. Mediation analysis offers a way of investigating how interventions work, by examining the extent to which an intermediate variable, or mediator, explains the effect of an intervention. This systematic review examined studies that used mediation analysis to investigate mechanisms of interventions on pain-relevant outcomes for youth (3–18 years) with acute or chronic pain, and provides recommendations for future mediation research in this field. We searched five electronic databases for clinical trials or observational longitudinal studies that included a comparison group and conducted mediation analyses of interventions on youth and assessed pain outcomes. We found six studies (N = 635), which included a total of 53 mediation models examining how interventions affect pain-relevant outcomes for youth. Five studies were secondary analyses of randomized controlled trials of psychological interventions for chronic pain; one was a longitudinal observational study of morphine for acute pain. The pain conditions studied were irritable bowel syndrome, functional abdominal pain, juvenile fibromyalgia, mixed chronic pain, and post-operative pain. Fourteen putative mediators were tested, of which three partially mediated treatment effect; seven did not significantly mediate treatment effect and four had mixed results. Methodological and reporting limitations were common. There are substantial gaps in the field with respect to investigating, and therefore understanding, how paediatric interventions work.

Development and validation of a shoulder-specific body-perception questionnaire in people with persistent shoulder pain

Background

There is evidence that people with persistent shoulder pain exhibit findings consistent with the presence of sensorimotor dysfunction. Sensorimotor impairments can manifest in a variety of ways, and further developing our understanding of sensorimotor dysfunction in shoulder pain may improve current models of care. The Fremantle Back Awareness Questionnaire (FreBAQ) has been developed to assess disturbed body perception specific to the back. The purpose of the present study was to develop a shoulder-specific self-perception questionnaire and evaluate the questionnaire in people with persistent shoulder pain.

Methods

The Fremantle Shoulder Awareness Questionnaire (FreSHAQ-J) was developed by modifying the FreBAQ. One hundred and twelve consecutive people with persistent shoulder pain completed the FreSHAQ-J. Thirty participants completed the FreSHAQ-J again two-weeks later to assess test-retest reliability. Rasch analysis was used to assess the psychometric properties of the FreSHAQ-J. Associations between FreSHAQ-J total score and clinical status was explored using correlational analysis.

Results

The FreSHAQ-J has acceptable category order, unidimensionality, no misfitting items, and excellent test-retest reliability. The FreSHAQ-J was moderately correlated with disability and pain catastrophization.

Conclusions

The FreSHAQ-J fits the Rasch measurement model well and is suitable for use with people with shoulder pain. Given the relationship between the FreSHAQ-J score and clinical status, change in body perception may be worth assessing when managing patients with shoulder pain.

Identifying participants with knee osteoarthritis likely to benefit from physical therapy education and exercise: A hypothesis-generating study

BACKGROUND

The purpose of this investigation was to undertake a hypothesis-generating study to identify candidate variables that characterize people with knee osteoarthritis who are most likely to experience a positive response to exercise.

METHODS

One hundred and fifty participants with knee osteoarthritis participated in this observational, longitudinal study. All participants received a standard exercise intervention that consisted of 20-min sessions two to three times a week for three months. The classification and regression tree methodology (CART) was used to develop prediction of positive clinical outcome. Positive pain and disability outcomes (dependent variables) were defined as an improvement in pain intensity by >50% or an improvement of five or more on the Oxford knee score, respectively. The predictor variables considered included age, sex, body mass index, knee osteoarthritis severity (Kellgren/Lawrence grade), pain duration, use of medication, range of knee motion, pain catastrophizing, self-efficacy and knee self-perception.

RESULTS

Fifty-five participants (36.6%) were classified as responders for pain intensity and 36.6% were classified as responders for disability. The CART model identified impairments in knee self-perception and knee osteoarthritis severity as the discriminators for pain intensity reduction following exercise. No variables predicted reduction of disability level following exercise.

CONCLUSIONS

Such findings suggest that both body perception and osteoarthritis severity may play a role in treatment outcome with exercise. It also raises the possibility that those with higher levels of disrupted body perception may need additional treatment targeted at restoring body perception prior to undertaking exercise.

SIGNIFICANCE

Regardless age, sex, body mass index, pain duration, use of medication, knee range of motion, pain catastrophizing and self-efficacy, participants with knee osteoarthritis who report low levels of body perception disruption (a FreKAQ score ≦ 17) and minimal structural changes (KL grade I) demonstrate significantly better outcomes from exercise therapy than other participants.

Prevalence and incidence of phantom limb pain, phantom limb sensations and telescoping in amputees: A systematic rapid review

BACKGROUND AND OBJECTIVE

This systematic, rapid review aimed to critically appraise and synthesize the recent literature (2014-2019) evaluating the incidence and prevalence of post-amputation phantom limb pain (PLP) and sensation (PLS).

DATABASES AND DATA TREATMENT

Five databases (Medline, Embase, Emcare, PsychInfo, Web of Science) and Google Scholar were searched, with two independent reviewers completing eligibility screening, risk of bias assessment and data extraction.

RESULTS

The search identified 1,350 studies with 12 cross-sectional and 3 prospective studies included. Studies evaluated traumatic (n = 5), atraumatic (n = 4), and combined traumatic/atraumatic (n = 6) amputee populations, ranging from 1 month to 33 years post-amputation. Study heterogeneity prevented data pooling. The majority of studies had a high risk of bias, primarily due to limited generalizability. Three studies evaluated PLP incidence, ranging from 2.2% (atraumatic; 1 month) to 41% (combined; 3 months) and 82% (combined; 12 months). Only one study evaluated PLS/telescoping incidence. Across contrasting populations, PLP point prevalence was between 6.7%-88.1%, 1 to 3-month period prevalence was between 49%-93.5%, and lifetime prevalence was high at 76%-87%. Point prevalence of PLS was 32.4%-90%, period prevalence was 65% (1 month) and 56.9% (3 months), and lifetime prevalence was 87%. Telescoping was less prevalent, highest among traumatic amputees (24.6%) within a 1-month prevalence period. Variations in population type (e.g. amputation characteristics) and incidence and prevalence measures likely influence the large variability seen here.

CONCLUSIONS

This review found that lifetime prevalence was the highest, with most individuals experiencing some type of phantom phenomena at some point post-amputation.

SIGNIFICANCE

This systematic rapid review provides a reference for clinicians to make informed prognosis estimates of phantom phenomena for patients undergoing amputation. Results show that most amputees will experience phantom limb pain (PLP) and phantom limb sensations (PLS): high PLP incidence 1-year post-amputation (82%); high lifetime prevalence for PLP (76%-87%) and PLS (87%). Approximately 25% of amputees will experience telescoping. Consideration of individual patient characteristics (cause, amputation site, pre-amputation pain) is pertinent given their likely contribution to incidence/prevalence of phantom phenomena.

Study protocol for a 9-month randomised controlled trial assessing the effects of almonds versus carbohydrate-rich snack foods on weight loss and weight maintenance

INTRODUCTION

Epidemiological studies indicate an inverse association between nut consumption and body mass index (BMI). However, clinical trials evaluating the effects of nut consumption compared with a nut-free diet on adiposity have reported mixed findings with some studies reporting greater weight loss and others reporting no weight change. This paper describes the rationale and detailed protocol for a randomised controlled trial assessing whether the inclusion of almonds or carbohydrate-rich snacks in an otherwise nut-free energy-restricted diet will promote weight loss during 3 months of energy restriction and limit weight regain during 6 months of weight maintenance.

METHODS AND ANALYSIS

One hundred and thirty-four adults aged 25-65 years with a BMI of 27.5-34.9 kg/m² will be recruited and randomly allocated to either the almond-enriched diet (AED) (15% energy from almonds) or a nut-free control diet (NFD) (15% energy from carbohydrate-rich snack foods). Study snack foods will be provided. Weight loss will be achieved through a 30% energy restriction over 3 months, and weight maintenance will be encouraged for 6 months by increasing overall energy intake by ~120-180 kcal/day (~500-750kJ/day) as required. Food will be self-selected, based on recommendations from the study dietitian. Body composition, resting energy expenditure, total daily energy expenditure (via doubly labelled water), physical activity, appetite regulation, cardiometabolic health, gut microbiome, liver health, inflammatory factors, eating behaviours, mood and personality, functional mobility and pain, quality of life and sleep patterns will be measured throughout the 9-month trial. The effects of intervention on the outcome measures over time will be analysed using random effects mixed models, with treatment (AED or NFD) and time (baseline, 3 months and 9 months) being the between and within factors, respectively in the analysis.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the University of South Australia Human Research Ethics Committee (201436). Results from this trial will be disseminated through publication in peer-reviewed journals, national and international presentations.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry (ACTRN12618001861246).

The RESOLVE Trial for people with chronic low back pain: statistical analysis plan

BACKGROUND

Statistical analysis plans describe the planned data management and analysis for clinical trials. This supports transparent reporting and interpretation of clinical trial results. This paper reports the statistical analysis plan for the RESOLVE clinical trial. The RESOLVE trial assigned participants with chronic low back pain to graded sensory-motor precision training or sham-control.

RESULTS

We report the planned data management and analysis for the primary and secondary outcomes. The primary outcome is pain intensity at 18-weeks post randomization. We will use mixed-effects models to analyze the primary and secondary outcomes by intention-to-treat. We will report adverse effects in full. We also describe analyses if there is non-adherence to the interventions, data management procedures, and our planned reporting of results.

CONCLUSION

This statistical analysis plan will minimize the potential for bias in the analysis and reporting of results from the RESOLVE trial.

TRIAL REGISTRATION

ACTRN12615000610538 (https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=368619).

The effect of multisensory illusions on pain and perceived burning sensations in patients with Burning Mouth Syndrome: A proof-of-concept study

BACKGROUND

Burning mouth syndrome (BMS) is a chronic pain disorder affecting the oral cavity. Previous work has shown promising analgesic results of bodily illusions in other chronic pain conditions. The aim of this proof-of-concept, pilot study was to investigate whether bodily illusions reduce pain in BMS patients.

METHODS

Nine participants diagnosed with BMS underwent bodily illusions using a MIRAGE-mediated reality system. All participants completed four conditions and performed standardised movements of the tongue. First, a baseline condition was performed while the tongue was viewed at normal size and colour. Then, three conditions were performed in random order: resizing shrink, colour-based (blue tongue) and incongruent movement illusions. During each condition, participants rated overall pain intensity and the intensity of burning pain/sensation on the tongue.

RESULTS

There was no difference in overall pain intensity ratings between conditions. However, a significant effect of condition was found for burning pain/sensation of the tongue. The colour illusion significantly reduced burning pain compared with baseline (MD = -12.8, 95% CI -20.7 to -4.8), corresponding to an average pain reduction of 32%. Exploratory analyses showed the colour illusion also significantly reduced pain compared with the shrink illusion (MD = -11.7, 95% CI -22.2 to -1.1).

CONCLUSION

Using visual illusions to change tongue colour to blue resulted in significant reductions in burning pain/sensations in BMS patients for the duration of the illusion. This proof-of-concept study suggests that BMS patients may benefit from bodily illusions, and supports additional research using larger samples and more comprehensive control conditions.

Implicit motor imagery performance is impaired in people with chronic, but not acute, neck pain

Background

People with chronic neck pain have impaired proprioception (i.e., sense of neck position). It is unclear whether this impairment involves disruptions to the proprioceptive representation in the brain, peripheral factors, or both. Implicit motor imagery tasks, namely left/right judgements of body parts, assess the integrity of the proprioceptive represention. Previous studies evaluating left/right neck judgements in people with neck pain are conflicting. We conducted a large online study to comprehensively address whether people with neck pain have altered implicit motor imagery performance.

Methods

People with and without neck pain completed online left/right neck judgement tasks followed by a left/right hand judgement task (control). Participants judged whether the person in the image had their head rotated to their left or right side (neck task) or whether the image was of a left hand or a right hand (hand task). Participants were grouped on neck pain status (no pain; <3 months—acute; ≥3 months—chronic) and pain location (none, left-sided, right-sided, bilateral). Outcomes included accuracy (primary) and response time (RT; secondary). Our hypotheses—that (i) chronic neck pain is associated with disrupted performance for neck images and (ii) the disruption is dependent on the side of usual pain, were tested with separate ANOVAs.

Results

A total of 1,404 participants were recruited: 105 reported acute neck pain and 161 reported chronic neck pain. When grouped on neck pain status, people with chronic neck pain were less accurate than people without neck pain (p = 0.001) for left/right neck judgements, but those with acute neck pain did not differ from those without neck pain (p = 0.14) or with chronic neck pain (p = 0.28). Accuracy of left/right hand judgements did not differ between groups (p = 0.58). RTs did not differ between groups for any comparison. When grouped on neck pain location, people were faster and more accurate at identifying right-turning neck images than left-turning neck images, regardless of history or location of pain (p < 0.001 for both); people with no pain were more accurate and faster than people with bilateral neck pain (p = 0.001, p = 0.015) and were faster than those with left-sided neck pain (p = 0.021); people with right-sided neck pain were more accurate than people with bilateral neck pain (p = 0.018). Lastly, there was a significant interaction between neck image and side of neck pain: people with right-sided neck pain were more accurate at identifying right-sided neck turning images than people with left-sided neck pain (p = 0.008), but no different for left-sided neck turning images (p = 0.62).

Conclusions

There is evidence of impaired implicit motor imagery performance in people with chronic neck pain, which may suggest disruptions to proprioceptive representation of the neck. These disruptions seem specific to the neck (performance on hand images intact) but non-specific to the exact location of neck pain.

The Influence of Auditory Cues on Bodily and Movement Perception

The sounds that result from our movement and that mark the outcome of our actions typically convey useful information concerning the state of our body and its movement, as well as providing pertinent information about the stimuli with which we are interacting. Here we review the rapidly growing literature investigating the influence of non-veridical auditory cues (i.e., inaccurate in terms of their context, timing, and/or spectral distribution) on multisensory body and action perception, and on motor behavior. Inaccurate auditory cues provide a unique opportunity to study cross-modal processes: the ability to detect the impact of each sense when they provide a slightly different message is greater. Additionally, given that similar cross-modal processes likely occur regardless of the accuracy or inaccuracy of sensory input, studying incongruent interactions are likely to also help us predict interactions between congruent inputs. The available research convincingly demonstrates that perceptions of the body, of movement, and of surface contact features (e.g., roughness) are influenced by the addition of non-veridical auditory cues. Moreover, auditory cues impact both motor behavior and emotional valence, the latter showing that sounds that are highly incongruent with the performed movement induce feelings of unpleasantness (perhaps associated with lower processing fluency). Such findings are relevant to the design of auditory cues associated with product interaction, and the use of auditory cues in sport performance and therapeutic situations given the impact on motor behavior.

What is the effect of bodily illusions on corticomotoneuronal excitability? A systematic review

Background

This systematic review aimed to summarise and critically appraise the evidence for the effect of bodily illusions on corticomotoneuronal excitability.

Methods

Five databases were searched, with two independent reviewers completing study inclusion, risk of bias, transcranial magnetic stimulation (TMS) reporting quality, and data extraction. Included studies evaluated the effect of an illusion that altered perception of the body (and/or its movement) on excitability of motor circuitry in healthy, adult, human participants. Studies were required to: use TMS to measure excitability and/or inhibition; report quantitative outcomes (e.g., motor evoked potentials); compare the illusion to a control or active comparison condition; evaluate that an illusion had occurred (e.g., measured illusion strength/presence).

Results

Of 2,257 studies identified, 11 studies (14 experiments) were included, evaluating kinaesthetic illusions (n = 5), a rubber hand illusion (RHI) paradigm (n = 5), and a missing limb illusion (n = 1). Kinaesthetic illusions (induced via vision/tendon vibration) increased corticomotoneuronal excitability. Conflicting effects were found for traditional, visuotactile RHIs of a static hand. However, embodying a hand and then observing it move (“self-action”) resulted in decreased corticomotoneuronal excitability and increased silent period duration (a measure of Gamma-Aminobutynic acid [GABA]_B-mediated intracortical inhibition in motor cortex), with the opposite occurring (increased excitability, decreased inhibition) when the fake hand was not embodied prior to observing movement (“other-action”). Visuomotor illusions manipulating agency had conflicting results, but in the lower risk study, illusory agency over movement resulted in a relative decrease in corticomotoneuronal excitability. Last, an illusion of a missing limb reduced corticomotoneuronal excitability.

Conclusion

While evidence for the effect of bodily illusions on corticomotoneuronal excitability was limited (only 14 experiments) and had a high risk of bias, kinaesthetic illusions and illusions of embodying a hand (and seeing it move), had consistent effects. Future investigations into the role of embodiment and the illusion strength on corticomotoneuronal excitability and inhibition are warranted.

Does readiness to change influence pain-related outcomes after an educational intervention for people with chronic pain? A pragmatic, preliminary study

Background: There is a strong association between chronic pain and unhelpful pain cognitions. Educating patients on pain neuroscience has been shown to reduce pain catastrophization, kinesiophobia, and self-perceived disability. This study investigated whether a group-based pain neuroscience education (PNE) session influenced pain-related outcomes, and whether readiness to change moderated these outcomes.Method: In a pragmatic pre-post-intervention study using a convenience sample, adults with chronic pain participated in one, 90-120 minute PNE session. Pain-related outcomes (i.e. pain catastrophization, kinesiophobia, disability, and pain neuroscience knowledge) and the Pain Stage of Change Questionnaire (PSOCQ) were assessed at baseline and immediately post-intervention. Paired t-tests evaluated pre-post changes in outcomes, and linear regression examined the impact of PSOCQ score changes on PNE-induced changes in clinical outcomes.Results: Sixty-five participants were recruited. All outcomes showed positive intervention effects (p < .01). Relationships between changes in PSOCQ subscale scores and change in post-intervention pain-related outcomes were found; 'Pre-Contemplation' was positively associated with pain catastrophization (p = .01), and 'Action' was negatively associated with kinesiophobia (p = .03).Conclusion: Consistent with previous research, there were improvements in outcomes associated with chronic pain after PNE. Some of these improvements were predicted by changes in PSOCQ scores, however, these findings are preliminary and require further investigation using controlled research designs.

Motor imagery in high-functioning individuals with chronic anterior cruciate ligament deficiency: A cross-sectional study

BACKGROUND

There is increasing evidence that motor imagery performance (MIP) is impaired in conditions that have a component of movement dysfunction. However, MIP has not been investigated in people with chronic anterior cruciate ligament (ACL) deficiency who experience limited disability and function at high levels.

HYPOTHESIS

This study had three objectives: (1) to assess implicit MIP in individuals with a chronic ACL deficient (ACLD) knee compared with healthy controls (i.e., intact anterior cruciate ligament); (2) to determine if the location of ACL deficiency affects MIP (dominant versus non-dominant leg); and (3) to determine if impairment in MIP is specific to the side (injured versus non-injured) of ACL deficiency.

METHODS

Forty-five participants with chronic ACLD knee and 44 healthy controls completed a left/right judgement task of pictured knees using the "Recognise" app to evaluate implicit MIP. Accuracy and reaction time of judgements were compared between groups. Additionally, within the chronic ACLD knee group, we made comparisons between the dominant ACLD knee and non-dominant ACLD knee subgroups and between the injured knee and the non-injured knee of the ACLD group.

RESULTS

There were no differences in implicit MIP between the ACLD knee and the control group, the non-injured knee versus injured knee of the ACLD knee group, or the dominant ACLD knee versus non-dominant ACLD knee subgroups.

CONCLUSION

Implicit MIP is not disrupted in high functioning individuals with chronic ACLD knee.

Pain Education for Adolescents and Young Adults Living Beyond Cancer: An Interdisciplinary Meeting Report

Pain is an understudied and undertreated consequence of cancer survival. Pain education is now a recommended treatment approach for persistent non-cancer pain, yet it has not been well applied to the context of adolescent and young adult (AYA) cancer survival. In March 2018, an interdisciplinary meeting was held in Adelaide, South Australia to set a research agenda for pain education in AYA cancer survivors. We identified that AYAs with persistent pain and those with heightened pain-related fear have the potential to benefit from pain education. We identified a number of unique challenges of engaging AYA survivors in pain education, and point towards future research directions.

Embodying the illusion of a strong, fit back in people with chronic low back pain. A pilot proof-of-concept study

OBJECTIVE

This proof-of-concept pilot study aimed to investigate if a visual illusion that altered the size and muscularity of the back could be embodied and alter perception of the back.

METHODS

The back visual illusions were created using the MIRAGE multisensory illusion system. Participants watched real-time footage of a modified version of their own back from behind. Participants undertook one experimental condition, in which the image portrayed a muscled, fit-looking back (Strong), and two control conditions (Reshaped and Normal) during a lifting task. Embodiment, back perception as well as pain intensity and beliefs about the back during lifting were assessed.

RESULTS

Two participants with low back pain were recruited for this study: one with altered body perception and negative back beliefs (Participant A) and one with normal perception and beliefs (Participant B). Participant A embodied the Strong condition and pain and fear were less and both perceived strength and confidence were more than for the Normal or the Reshaped condition. Participant B did not embody the Strong condition and reported similar levels of pain, fear strength and confidence across all three conditions.

DISCUSSION

An illusion that makes the back look strong successfully induced embodiment of a visually modified back during a lifting task in a low back pain patient with altered body perception. Both participants tolerated the illusion, there were no adverse effects, and we gained preliminary evidence that the approach may have therapeutic potential.

Illusory resizing of the painful knee is analgesic in symptomatic knee osteoarthritis

BACKGROUND

Experimental and clinical evidence support a link between body representations and pain. This proof-of-concept study in people with painful knee osteoarthritis (OA) aimed to determine if: (i) visuotactile illusions that manipulate perceived knee size are analgesic; (ii) cumulative analgesic effects occur with sustained or repeated illusions.

METHODS

Participants with knee OA underwent eight conditions (order randomised): stretch and shrink visuotactile (congruent) illusions and corresponding visual, tactile and incongruent control conditions. Knee pain intensity (0-100 numerical rating scale; 0 = no pain at all and 100 = worst pain imaginable) was assessed pre- and post-condition. Condition (visuotactile illusion vs control) × Time (pre-/post-condition) repeated measure ANOVAs evaluated the effect on pain. In each participant, the most beneficial illusion was sustained for 3 min and was repeated 10 times (each during two sessions); paired t-tests compared pain at time 0 and 180s (sustained) and between illusion 1 and illusion 10 (repeated).

RESULTS

Visuotactile illusions decreased pain by an average of 7.8 points (95% CI [2.0-13.5]) which corresponds to a 25% reduction in pain, but the tactile only and visual only control conditions did not (Condition × Time interaction: p = 0.028). Visuotactile illusions did not differ from incongruent control conditions where the same visual manipulation occurred, but did differ when only the same tactile input was applied. Sustained illusions prolonged analgesia, but did not increase it. Repeated illusions increased the analgesic effect with an average pain decrease of 20 points (95% CI [6.9-33.1])-corresponding to a 40% pain reduction.

DISCUSSION

Visuotactile illusions are analgesic in people with knee OA. Our results suggest that visual input plays a critical role in pain relief, but that analgesia requires multisensory input. That visual and tactile input is needed for analgesia, supports multisensory modulation processes as a possible explanatory mechanism. Further research exploring the neural underpinnings of these visuotactile illusions is needed. For potential clinical applications, future research using a greater dosage in larger samples is warranted.

A feasibility study of brain-targeted treatment for people with painful knee osteoarthritis in tertiary care

Purpose: To assess the feasibility and clinical impact of brain-targeted treatment (BT; aiming to target sensorimotor processing) in knee osteoarthritis patients attending tertiary care. Methods: Randomized replicated case series. The study involved three phases, each of 2 weeks duration: (1) no-treatment phase; (2) BT phase (left/right judgments and touch discrimination training); and (3) usual care (education, strengthening, and stretching training). Primary outcomes were: timely recruitment; number of participants completing the interventions; treatment compliance and barriers; follow-up rates; and treatment impact on pain and function. Fear-avoidance beliefs and clinical measures of cortical body representation (tactile acuity and left/right judgment performance) were secondary outcomes. Results: A total of 5% (19/355) of all assessed patients were eligible to participate and of these, 58% (11/19) agreed to participate. Ten patients completed the study, and 9 were successfully followed up, with treatment compliance varying between interventions. Compliance was poor for the touch discrimination component of BT. No significant effects were observed for pain relief or knee function after any treatment. A positive impact of treatment was found for fear-avoidance beliefs (usual care vs. washout, p = 0.007; BT vs. washout, p = 0.029) and left/right judgment accuracy (usual care vs. washout; p = 0.006). Conclusions: Clear barriers were identified to implementing BT in tertiary care for knee osteoarthritis. Access to all available services (especially the use of interpreters), and treatment options that do not require additional assistance to perform (e.g., touch discrimination training) represent the main lessons learned.

Feeling stiffness in the back: a protective perceptual inference in chronic back pain

Does feeling back stiffness actually reflect having a stiff back? This research interrogates the long-held question of what informs our subjective experiences of bodily state. We propose a new hypothesis: feelings of back stiffness are a protective perceptual construct, rather than reflecting biomechanical properties of the back. This has far-reaching implications for treatment of pain/stiffness but also for our understanding of bodily feelings. Over three experiments, we challenge the prevailing view by showing that feeling stiff does not relate to objective spinal measures of stiffness and objective back stiffness does not differ between those who report feeling stiff and those who do not. Rather, those who report feeling stiff exhibit self-protective responses: they significantly overestimate force applied to their spine, yet are better at detecting changes in this force than those who do not report feeling stiff. This perceptual error can be manipulated: providing auditory input in synchrony to forces applied to the spine modulates prediction accuracy in both groups, without altering actual stiffness, demonstrating that feeling stiff is a multisensory perceptual inference consistent with protection. Together, this presents a compelling argument against the prevailing view that feeling stiff is an isomorphic marker of the biomechanical characteristics of the back.